This invention relates to fire suppression, and more particularly to fire extinguishers which may be installed within vehicles.
There are a wide variety of fire extinguishing technologies and fire extinguisher constructions. These include propellant-actuated extinguishers and extinguishers charged with compressed and/or liquified gas.
The basic features of an early propellant-actuated extinguisher are seen in U.S. Pat. No. 2,530,633 (Scholz). Scholz discloses a fire extinguisher wherein xe2x80x9ca liquid extinguishing medium, such as methyl bromide, is expelled from its container by gas evolved from the burning ofxe2x80x9d a pyrotechnic charge. The charge is originally stored in a container which includes electric squibs. The charge container is mounted in an upper end of the vessel within a xe2x80x9ccontainer cupxe2x80x9d. Opposite the container cup, an outlet from the vessel is formed by an elbow fitting sealed by a rupturable diaphragm. Ignition of the pyrotechnic charge ruptures a wall of the charge container and vents combustion gases into the vessel. The combustion gases serve xe2x80x9cas a gas piston acting on the surface of the liquidxe2x80x9d rupturing the diaphragm which sealed the outlet and propelling the liquid out of the extinguisher.
The application of a propellant-actuated extinguisher to use in military vehicles is described in U.S. Pat. No. 4,319,640 (Brobeil). Brobeil discloses an extinguisher in many ways similar to Scholz. The exemplary fire suppressant utilized is Halon 1301. The lower end of the extinguisher vessel is sealed by a rupturable diaphragm. A as generating device is mounted atop the neck of the vessel. The exemplary gas generating composition is 62% sodium azide and 38% copper oxide.
U.S. Pat. No. 5,660,236 (Sears et al.) discloses the application of pressure from a gas generator to an annular piston which compresses a fire suppressant located in a central portion of a cylindrical container. This in turn induces the rupture of rupturable disks separating the suppressant from an apertured end portion of the cylindrical container. A portion of the combustion gas bypasses the piston and flows directly to the apertured end portion where it assists in vaporizing the fire suppressant and driving such suppressant from the extinguisher.
U.S. Pat. No. 4,889,189 (Rozniecki) discloses an extinguisher which utilizes a poppet-type xe2x80x9cflush valvexe2x80x9d. A bladder separates a first chamber containing the suppressant from a second chamber to which the pressurizing gas is admitted. The bladder stretches on pressurization of the second chamber to drive the suppressant from the first chamber. The flush valve (mounted centrally within the bladder) opens once the bladder has reached its maximum stretch (having reduced the space occupied by the first chamber to a small fraction of the total container volume and driven nearly all of the suppressant from the container). The opening of the flush valve allows the propellant gas to be vented from the second volume through the first volume taking with it substantially the remainder of any suppressant.
U.S. Pat. No. 4,579,315 (Kowalski) discloses a pressurized Halon 1301 extinguisher. The extinguisher outlet is normally closed by a poppet valve. The poppet is held in its closed position by a latch which is released by a solenoid and thereby allows the pressure within the cylinder to drive the poppet to an open position.
U.S. Pat. No. 2,557,957 (Ferguson) discloses a manually-actuated, gas-pressurized aircraft fire extinguisher. The pressurant and suppressant are initially held in separate chambers. The two chambers are initially separated by both a membrane or closure and a sliding piston. The closure is ruptured via a manually-actuated piercing device, allowing the pressurant to drive the piston against the suppressant. The piston carries a poppet valve which opens once the piston has reached the end of its travel, allowing the pressurant to drive any residual suppressant from the extinguisher.
U.S. Pat. No. 3,861,474 (De Palma) discloses a dry chemical extinguisher utilizing a compressed gas pressurant. The outlet is normally sealed via mating of a first valve head with a seat. An outer tube circumscribes the seat and depends therefrom extending down and into the body of dry chemical. Concentrically within the outer tube is an inner tube. The lower end of the inner tube is normally sealed by a second valve head. Initially, both the ullage space and the inner tube are pressurized. The valve may be actuated manually or automatically. The automatic actuation is achieved via heating of gas within a bellows. Expansion of the bellows acts to disengage both the first head from its seat and the second head from the lower end of the inner tube. Although gas within the ullage space pushes down on the dry chemical, gas escaping from the inner tube entrains the dry chemical in an upward flow through the annular space between the inner and outer tubes.
U.S. Pat. No. 4,034,813 (Le Day) discloses a gas-pressurized extinguisher closed by a poppet valve having a head upstream and a valve extending downstream. The valve is held in a closed position by a pin having a pivoting end and a free end. The free end of the pin is held by a body of wax or a low melting point alloy. Heat from a fire softens the body, allowing the pressure within the extinguisher to drive the valve into an open position.
U.S. Pat. No. 4,159,744 (Monte et al.) discloses a nitrogen-pressurized extinguisher. The suppressant bottle is sealed by a poppet-type valve wherein the head faces the body of suppressant and the stem is directed outward. The valve opens into the bottle and is activated by either a squib or explosive cartridge acting upon a piston which bears against the stem.
There remains a further need for a high-performance fire extinguisher useful in vehicles and other enclosed spaces.
One aspect of the invention is directed to a fire extinguisher comprising a bottle having an interior and a fire suppressant contained by the bottle when the extinguisher is in a pre-discharge condition. A source of gas pressurizes the suppressant at least when the bottle is in a discharging condition and the suppressant is discharged through an outlet when the extinguisher is in the discharging condition. A valve has a valve element having a closed position sealing the outlet and an open position permitting discharge of the suppressant through the outlet. The valve element is shiftable from the closed position to the open position responsive to a pressure within the bottle exceeding a discharge threshold pressure, whereupon the extinguisher enters the discharging condition and discharges the suppressant through the outlet.
In various implementations, the valve element may comprise a poppet having a head and a stem connected to the head. The head may have a fore surface facing the bottle interior and an opposite aft face from which the stem extends along a poppet axis. The valve may have a locking element which in the pre-discharge condition has a first portion engaged to the poppet and a second portion held relative to the bottle. In the pre-discharge condition the locking element transmits force to the poppet which retains the poppet in the closed position and, responsive to the pressure within the bottle exceeding the discharge threshold pressure the locking element ruptures, whereupon the pressure within the bottle drives the poppet to the open position and the extinguisher enters the discharging condition. A valve return spring may bias the poppet toward the closed position. The return spring is effective to return the poppet from the open position to the closed position when the fire suppressant has been substantially discharged from the extinguisher.
The valve element may comprise a head having a fore face facing the bottle interior and an opposite aft face and a collapsible shaft between the head and a valve body. In the pre-discharge condition, when the pressure within the bottle is lower than the discharge pressure, axial compression of the shaft may be effective to resist rearward movement of the head and retain the head in the closed position. Responsive to the pressure within the bottle exceeding the discharge threshold pressure the shaft may collapse via buckling, whereupon the pressure within the bottle drives the head to the open position and the extinguisher enters the discharging condition. The source of gas may comprise a chemical propellant charge. The chemical propellant charge may have a combustion temperature of less than about 1500xc2x0 F. (816xc2x0 C.). The chemical propellant charge may have gaseous combustion products consisting essentially of nitrogen, carbon dioxide, water vapor and mixtures thereof. The chemical propellant charge may consist essentially of a mixture of 5-aminotetrazole, strontium nitrate, and magnesium carbonate.
The source of gas may comprise a replaceable cartridge containing a chemical propellant charge. A cartridge holder assembly may hold the cartridge and may have a first end mounted within an aperture at an upper end of the bottle and a second end immersed within the suppressant when the extinguisher is in the pre-discharge condition. A closure, may close the first end. A replaceable squib may be mounted within the closure. The discharge threshold pressure may be between about 300 psi (2.1 MPa) and about 1500 psi (10.3 MPa). The fire suppressant may be selected from the group consisting of PFC""s, HFC""s, water, and aqueous solutions.
In another aspect, the invention is directed to a fire extinguisher having a bottle extending along a longitudinal axis from a first opening at a first end to a second opening at a second end, opposite the first end. The bottle may comprise the combination of a first piece extending longitudinally inboard from a mouth at the first end and a second piece extending longitudinally inboard from a mouth at the second end. The mouth of the second piece is substantially identical to the mouth of the first piece. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A source of gas pressurizes the suppressant at least when the bottle is in a discharging condition. The suppressant is discharged through an outlet when the extinguisher is in the discharging condition.
In various implementations of the invention, the first and second pieces may be substantially identical. The first and second pieces may meet at an annular weld. The source of gas may comprise a propellant charge carried by a fixture secured within the mouth of the first piece. The outlet may be formed in a discharge assembly carried within the mouth of the second piece.
In another aspect, the invention is directed to a method for manufacturing a fire extinguisher. First and second pieces are provided each having a feature for engaging either one of a gas generator assembly and a discharge head assembly. The first and second pieces are assembled to form a bottle. The first and second pieces are optionally further modified. A discharge head assembly is provided. A gas generator assembly is provided. A fire suppressant is provided. The discharge head assembly is installed in the first piece of the assembled bottle. The gas generator assembly is installed in the second piece of the assembled bottle. The assembled bottle is filled with the suppressant. The assembling of the first and second pieces may comprise welding the first and second pieces together at a transverse centerplane of the bottle.
In another aspect, the invention is directed to a fire extinguisher comprising a bottle extending along a longitudinal axis from a first opening at a first end to a second opening at a second end, opposite the first end. The bottle has a failure pressure. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A source of gas pressurizes the suppressant at least when the bottle is in a discharging condition. The suppressant is discharged through an outlet when the extinguisher is in the discharging condition. A poppet has a head and a stem connected to the head. The head has a fore face and an opposite aft face from which the stem extends along a poppet axis. The poppet has a closed position normally sealing the outlet and an open position permitting discharge of the suppressant through the outlet. The head has a preferential rupture zone which, upon an internal pressure in the extinguisher exceeding a safety threshold pressure ruptures so as to permit discharge of suppressant from the extinguisher, reducing the internal pressure and preventing the internal pressure from rising to within a safety margin of said failure pressure.
In various implementations of the invention, the preferential rupture zone may be proximate an annular groove in the head so that upon such rupture an annular peripheral portion of the head detaches from a core portion of the head. The fore face of the head may face the bottle interior. The source of gas may comprise a chemical propellant charge which, upon ignition elevates the internal pressure. In normal operation the poppet may be shiftable from the closed position to the open position responsive to the pressure within the bottle exceeding a discharge threshold pressure, less than said safety threshold pressure, whereupon the extinguisher enters the discharge condition and discharges the suppressant through the outlet. The safety threshold pressure may be between about 1000 psi (6.9 MPa) and about 2000 psi (13.8 MPa) and the discharge threshold pressure may be between about 300 psi (2.1 MPa) and about 1500 psi (10.3 MPa). The safety threshold pressure may be between about 1000 psi (6.9 MPa) and about 3000 psi (20.7 MPa).
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fluid fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. The extinguisher has a preferred orientation for use in a gravitational field. In such preferred orientation the suppressant extends upward from a low point within the bottle interior to a surface level at a first height in the pre-discharge condition. The suppressant is discharged through an extinguisher outlet when the extinguisher is in the discharging condition. A chemical propellant charge combusts to produce combustion gasses which are introduced to the suppressant through a combustion gas outlet and elevate an internal pressure of the extinguisher above an initial pressure. The combustion outlet is located below the first height by a distance effective to cause mixing of the combustion gasses and the suppressant so that the suppressant discharged from the extinguisher is substantially mixed with at least a portion of said combustion gasses.
In various implementations of the invention, the suppressant may have a surface at the first height and the bottle interior contains an ullage space above the surface. The combustion outlet may be located within a lower half of a vertical distance from the extinguisher outlet to the first height. The combustion outlet may be located within a lower third of a volume of the suppressant. The combustion outlet may comprise a plurality of apertures positioned to direct the combustion gasses radially outward. The chemical propellant charge may have a combustion temperature of less than about 1500xc2x0 F. (816xc2x0 C.).
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A replaceable cartridge contains a chemical propellant charge. A cartridge holder assembly holds the cartridge and has a first end mounted within an aperture at an upper end of the bottle. A second end is immersed within the suppressant when the extinguisher is in the pre-discharge condition. A closure, closes the first end. A squib is mounted within the closure for igniting the propellant. A gas generator release poppet is spring biased toward a first position in which it blocks a path between the cartridge and the suppressant. Upon combustion of the propellant it shifts under pressure applied by combustion gasses to a second position wherein such path is unblocked and the combustion gasses may communicate with and pressurize the suppressant. The suppressant is discharged through an outlet responsive to the pressurization of the suppressant. A discharge poppet may close the outlet when the extinguisher is in its pre-discharge condition.
In another aspect, the invention is directed to a method for remanufacturing a discharged fire extinguisher. A spent propellant cartridge is removed from a cartridge holder mounted within an extinguisher bottle. A probe is inserted into the cartridge holder, causing the probe to seal with a sealing surface of the cartridge holder. A refill amount of fluid fire suppressant is delivered through the probe into a bottle interior the probe is extracted from the cartridge holder. A replacement propellant cartridge is inserted into the cartridge holder.
In various implementations of the invention, the insertion of the probe may cause a tip of the probe to depress a gas generator release poppet from a first position to a second position. In the first position the gas generator release poppet blocks a path between an interior portion of the cartridge holder and an interior portion of the bottle external to the cartridge holder. In the second position such path is unblocked and the refill amount of fluid fire suppressant may be delivered along such path. The extraction of the probe may allow the gas generator release poppet to return to the first position. A closure may be removed from the cartridge holder to permit the removal of the spent cartridge. A spent squib from the closure. The spent squib may be replaced with a fresh squib. The closure may be replaced so as to secure the replacement propellant cartridge within the cartridge holder.
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition and a replaceable cartridge contains a chemical propellant charge. A cartridge holder holds the cartridge and has a first end mounted within an aperture at an upper end of the bottle. A second end is immersed within the suppressant when the extinguisher is in the pre-discharge condition. A closure closes the first end. A squib is mounted within the closure for igniting the propellant. A replaceable gas generator relief plug initially seals a path between the cartridge and the suppressant. The plug has a centrally apertured metal body and a metal flap member initially secured to the metal body at least in part by a braze or solder joint which upon combustion of the propellant, pressure applied to the flap by combustion gasses emitted by the propellant is effective to rupture the joint so as to allow the flap to assume a position wherein such path is unsealed and the combustion gasses may communicate with and pressurize the suppressant. The suppressant is then discharged through an outlet responsive to the pressurization of the suppressant.
In various implementations of the invention, prior to combustion of the propellant the flap may have a first transversely extending portion secured by said joint to the body and a second longitudinally extending portion secured to the body by a second joint. The second joint may be a braze, a weld, or a solder joint.
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A gas generator assembly has a chemical propellant charge, and a body having at least one piece. The body has a first end mounted within an aperture at an upper end of the bottle. A second end is immersed within the suppressant when the extinguisher is in the pre-discharge condition. An initiator ignites the propellant. A gas generator relief poppet initially seals a path between the propellant and the suppressant. The poppet has a head having a fore surface facing the propellant and an aft surface and having a perimeter portion engaged to the body. A stem extends aft from the head. Upon combustion of the propellant, pressure applied to the head by combustion gasses emitted by the propellant is effective to rupture the head so as to separate a remainder of the gas generator relief poppet from the perimeter portion and allow the remainder to assume a position wherein such path is unsealed and the combustion gasses may communicate with and pressurize the suppressant. The suppressant is then discharged through an outlet responsive to the pressurization of the suppressant. In the pre-discharge condition movement of the discharge poppet toward the propellant may be prevented by interaction of a protuberance at a distal end of the stem with the gas generator assembly body about an aperture through which the stem passes.
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A replaceable cartridge contains a chemical propellant charge. A cartridge holder assembly holds the cartridge and has a first end mounted within an aperture at an upper end of the bottle. A second end is immersed within the suppressant when the extinguisher is in the pre-discharge condition. A closure closes the first end. An initiator assembly mounted within the closure ignites the propellant and has a body, a replaceable percussion cap primer having a primer charge, a firing pin, a spring, and a solenoid. The solenoid has a fixed coil and a plunger, coupled to the firing pin by a sear and shiftable, by energizing of the coil, from a first position at least to a second position. Such a shift draws the firing pin away from the primer until the plunger reaches the second position, whereupon release of the sear allows the firing pin to be driven by the spring to impact the primer and cause ignition of the primer charge which in turn causes ignition of the chemical propellant charge so as to pressurize the suppressant and discharge the suppressant from the extinguisher.
In various implementations of the invention, there may be a mechanism for manually shifting the plunger from the first position to the second position in the absence of energizing of the coil so as to provide a manual actuation of the extinguisher. There may be a control system for energizing the coil in response to: input from a fire sensor, and input from a manually actuatable switch providing manual actuation of the extinguisher.
In another aspect, the invention is directed to a fire extinguisher comprising a bottle having an interior. A fire suppressant is contained by the bottle when the extinguisher is in a pre-discharge condition. A holder assembly holds a chemical propellant charge and has a first end mounted within an aperture at an upper end of the bottle. A second end is immersed within the suppressant when the extinguisher is in the pre-discharge condition. A closure closes the first end. An initiator assembly is mounted within the closure for igniting the propellant and comprises triggering means for: (a) electrically triggering ignition of the propellant; and (b) mechanically triggering ignition of the propellant independent of electrical triggering.
The triggering means may comprise a squib for electrically triggering ignition of the propellant, and a percussion primer for mechanically triggering ignition of the propellant. The triggering means may comprise a replaceable percussion cap primer having a primer charge, a firing pin, a spring, and a solenoid. The solenoid may have a fixed coil and a plunger, coupled to the firing pin by a sear and shiftable, by energizing of the coil, from a first position at least to a second position. Such a shift may draw the firing pin away from the primer until the plunger reaches the second position, whereupon release of the sear allows the firing pin to be driven by the spring to impact the primer and cause ignition of the primer charge so as to provide the electrical triggering. There may also be a mechanism for manually shifting the plunger from the first position to the second position in the absence of energizing of the coil so as to provide the mechanical triggering.
Another aspect of the invention is directed to a method for remanufacturing a discharged fire extinguisher. A spent propellant container is removed from an extinguisher bottle. A replacement propellant container is inserted into the bottle. A discharge valve head and a collapsed shaft are removed from a discharge head assembly. The discharge valve head and collapsed shaft are replaced with a replacement head having a fore face facing the bottle interior and an opposite aft face: and a replacement collapsible shaft. A refill amount of fluid fire suppressant is delivered through a fill valve into a bottle interior.
The removal of the discharge valve head and the collapsed shaft from the discharge head assembly may involve unscrewing a discharge head end closure from an aperture of a body of the discharge head. The discharge head end closure may have a socket initially accommodating an aft end of the collapsed shaft. The discharge valve head and the collapsed shaft may be extracted through the aperture. The discharge head end closure may be replaced so that the socket accommodates an aft end of the replacement collapsible shaft. The bottle interior may be evacuated through the fill valve prior to delivering the refill amount of fluid fire suppressant.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.